A comparison between in vivo radiographic working length determination and measurement after extraction

By Williams CB, Joyce AP, Roberts S.

Date: 10/2007
Journal: JOE


Purpose: To compare the difference between the in vivo working length established by EAL and PA radiographs and the in vitro measurement from the file tip to the apical foramen of the extracted tooth


n: 11 patients with 26 canals in teeth indicated for extraction.

The teeth were accessed and coronally enlarged by GG #2-#4 followed by a k-file insertion to the apex using EAL (Root ZX) then the file was cemented to the WL length using GIC cement and PA radiographs were taken. Teeth were then extracted and the distance was measured between the file tip and the most coronal part of the major foramen using videomicrometer microscope

-6 dentist examined the WL radiographs and evaluated the distance from the file tip to the radiographic apex as overestimation or underestimation of file position. –


-Examiners underestimated the distance of the file that exceeded the major foramina by 61% as illustrated in Table.1.

-Examiners overestimated the distance of the file that was shorter than the microscopic WL by 63% as illustrated in Table.1.

Cclinical consideration:

When the file is short, it is actually closer to the apical foramen by an average of 0.46 mm than it appears radiographically. When the file is long, it is actually longer by an average of 1.2 mm than it appears radiographically